pretty sure it's a plugin issue ...openeing in saf mode is the key 

 Ok, holding down shift while clicking on the icon (or hitting "Enter" or whatever) makes no difference. It still brings up the "SONAR" splash screen, and then hangs.

When you open Sonar in safe mode, the first thing you should get is a dialog that says "SONAR will now personalize your user settings..." Are you not getting this dialog and going straight to a splash screen? btw, safe mode isn't a Mac or PC thing, it's a Sonar thing.

 Ah, yes I do get that message. However, regardless of my response, I get the same result.

If you can't get started in safe mode, I fear you may be into uninstall/reinstall territory.

Might be worth contacting support to see if they have any other ideas.

Make sure you keep holding down shift after you launch the program. If you get past the splash screen, Sonar will go through each of the plugins on at a time in your template (assuming you have any in it) and ask if you want to load them. Then you narrow it down to the problem plugin. If you can't get to that stage, though, you'll probably need to call tech support.

I have the exact same problem running Sonar X3 on Windows 10. Has anyone found any solutions? I have thousands invested here and I can't work without it. Please help if you can.

You're better off starting a new thread Andy - this one is 6 years old and things have moved on
It will also help if you included details for your entire system - including pc specs, interface, driver etc